The present invention relates to opto-electronic transceiver modules and, more particularly, to structures of and methods of making subassemblies in a module for coupling a multiple channel fiber optic cable to a multiple channel transmitter comprising a Vertical Cavity Surface Emitting Laser (VCSEL) transmitter and to a multiple channel receiver comprising a photodetector and a transimpedance amplifier commonly referred to as a Preamplifier with Integrated Detector (PAID).
An opto-electronic transceiver is the key component in a parallel fiber optic data link. One such transceiver is a modular package or module for coupling a multiple channel fiber optic cable to a multiple channel Vertical Cavity Surface Emitting Laser (VCSEL) and to a multiple channel receiver. The module consists of various components, including both CMOS and opto-electronic dies (chips). It is designed to accept a single connector that has one receive and one transmit section and is mounted on the end of a dual 12-channel fiber optic ribbon cable. The transit half of the module converts parallel electrical input signals into their corresponding parallel optical output signals through a laser driver and a Vertical Cavity Surface Emitting Laser (VCSEL) diode array. The receive half of the module converts parallel optical input signals into corresponding parallel electrical output signals by using an array of photodetectors and transimpedance amplifiers to convert the optical input signals to voltage signals. This arrangement of photodetector and amplifier is commonly referred to as a xe2x80x9cPAIDxe2x80x9d (Preamplifier with Integrated Detector). The module also includes driver chips which communicate data signals to the transmitter and receiver chips.
The optoelectronic transceiver module comprises a number of major building blocks. One is an overmolded laminate subassembly that incorporates electronic functions using standard manufacturing materials. The second is a retainer subassembly that incorporates optical and other components necessary to support the module""s optoelectronic, optical and connector functions. The retainer subassembly includes both a receiver optical subassembly (ROSA) and a transmitter optical subassembly (TOSA). The module is assembled by mounting the retainer subassembly on the overmolded laminate subassembly and electrically connecting the two subassemblies. A heat sink is a third major component since it is important to efficiently remove heat which is generated by all chips. An EMI (electromagnetic Interference) shield is also attached.
Although the driver chips are buried in the overmold, and lie substantially perpendicularly to the transmitter and receiver chips, the heat sink must function to remove heat from all chips. Additionally, the transmitter and receiver chips are located in proximity to each other, but cross-talk therebetween must be avoided. Finally, an assembly methodology must be used which is repeatable, reliable, and meets the required assembly tolerances.
In accordance with the present invention, an optoelectronic module is provided having the following advantages:
a) Improved removal of heat from the optoelectronic chips,
b) Elimination of cross-talk between chips using simplified structure,
c) Simplified and reliable assembly methodology, and
d) Package size reduction.
In accordance with an aspect of the invention, in an electronic module including an optical coupler and a plurality of chips, each of which is located in a mount, wherein two such mounts lie in a common plane and a third mount lies in a substantially perpendicular plane to the common plane, an improved heat sink is provided comprising first and second metallic surfaces which are parallel to the common plane and which overlie the area occupied by first and second chips, and a third metallic surface which is substantially parallel to the perpendicular plane and which overlies the area occupied by other chips.
In accordance with further aspects of the invention, improved retainers for optical couplers are provided as are improved chip carriers and overmolds, as well as improved methods of securing the optical retainer in the coupler, and of bonding flexible leads to the chip carrier.